h1,h2,body{
    margin: 0;
    padding: 0;
}
.nav-bar{
    display: flex;
    height: 40px;
    line-height: 40px;
    text-align: center;
    align-items: center;
}
.left, .right{
    width: 80px;
    background-color:  #f00;
}
.center{
    flex: 1;
    background-color: #f80;
}